{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular}{l*{1}{c}}
\toprule
                    &\multicolumn{1}{c}{Assigned to treatment}\\\cmidrule(lr){2-2}
                    &\multicolumn{1}{c}{(1)}         \\
\midrule
Recruited from BA listserv&       0.016         \\
                    &     [0.040]         \\
\addlinespace
partyID\_merged\_D    &       0.008         \\
                    &     [0.053]         \\
\addlinespace
partyID\_merged\_R    &       0.002         \\
                    &     [0.061]         \\
\addlinespace
Qualtrics: Previously attended BA event (clean)&      -0.073\sym{**} \\
                    &     [0.037]         \\
\midrule
Observations        &         900         \\
\bottomrule
\end{tabular}
}
